Following the advice here, I picked up a Horstmann DRT2 programmable 'stat, to replace the Danfoss RT230 I had ...
Just a quick Q about the wiring ... the RT230 has a red (Live ?) going to terminal 4, and a blue (neutral ?) going to terminal 1. Looking at the DRT2 instructions, they say Live should go to "COM" and Neutral to "NO".
So red wire goes to "COM" and blue to "NO" - and we're off ?
Old stat is still fixed in, jic !!!!!
Thanks guys
You seem to be one wire short of a circuit.
I cannot find an RT230, but it looks like the RT series have a neutral connection for hysteresis heater. Are you sure there are not three wires (excluding any earth) connected to the old stat?
The DRT2 instructions do not say to connect the neutral to "NO". It is battery powered so only needs two wires, live feed and switched live feed to boiler/pump. Any neutral should be insulated. he live wire goes to COM and the switched feed to the boiler goes to "NO"
If there are only two wires to your existing stat, then in all probability they are live and switched live.
John
Thanks, I shall have to read everything much more carefully ... tomorrow at leisure.
I think you were spot on (I confess, I dug up an old control theory textbook to confirm my memory of "hysteresis").
So I insulated the blue wire away, and connected the live to COM and switched live (which was the earth wire with a red sleeve) to "NO".
All tested and working - so very happy bunny. If nothing else, I now have a thermometer the Mrs can see, when I tell her it's not that cold ...
So give her a couple of asprins the next time she
Could I suggest reusing the blue wire as a conductor?
Now that's worrying ....
Not sure what you mean ? I checked the connections to the old 'stat, and sure enough, when it was "on" the live and switched live terminals were closed circuit. When I twiddled the dial and the 'stat went off, they went open circuit.
Like I said, I tested it as is, and it works spot on ... so not sure what else I should do with the blue wire (and in response to the usual jokers, it could be a bit scratchy :) )
Ah, just found
I think what Adam means is that using the earth conductor for the switched live is "poor form" and if you can use the now spare blue wire as the switched live (Sleeved at the end with a red sleeve) it would be a "proper job". The original thermostat should have been connected with a cable having three wires plus earth, but the installer did it on the cheap with presumably what was to hand.
John
Ah, I did wonder. The heating system was completely gutted and replaced in 2002, and I had no part in it at all (it was a recommended plumber who subbed out the electrics). I shall have a little shufty and see if I can amend it to be "nice".
That is what I meant.
But there is now a mystery. The OP said that he had the work done in 2002, now thats pre colour change.
So there would only be a blue wire if it is a flex or a 3 core and earth. I wonder if Jethro means that the yellow core of a 3 core and earth was used as the switched live?
Actually, it was 3 core & earth ... I never gave it a thought, but yes, you're right, it's pre colour change ... can't explain why ...
Because it was before 2004/blonde moment/senior moment:-)
And is it (please confirm) that the yellow core with a red oversleeve is used for the switched live wire and not the cpc (AKA the earth) ?
If it is the yellow wire, then RESULT, your electrician did a proper job and so did you.
If it was the cpc that was used then you should consider a small upgrade.
OK ... here's what I have now ... 3 core + uninsulated wire. Blue (which went to the "4" connection on the old 'stat) - now disconnected & insulated
Red - (was connected to "1") goes to "COM" on new 'stat
Yellow with red sleeve (went to "2" on old 'stat) now goes to "NO"
Uninsulated wire - still goes to metal backbox (although neither stat was in the box, but over it)
As I said I had to refresh my memory of hysteresis (fond memories of programming a robot crane to swing a weight with zero recoil, and an assembler program to drive a heater and fan assembly) to understand why there was a neutral connection. But having removed the old stat, I confirmed it was switching 1 and 2, which are the wires I reused.
Bloody hell, I think we got there. I only answered my own post to archive this in case anyone else has the same job to do. Thanks as always guys - please have a virtual pint on me !
A perfect job. Sorry to have asked you twice. I must have gone Irish "to be sure to be sure".
And the wife is happy?
I am happy that you have a safe intall. BTW virtual bottles of wine are just as cheap as a pint:-)
No ... better safe than sorry.
(checks over shoulder) in as much as any woman is :)
Ah, well accept 2 bottles in that case ... personally I would have a Chablis and a Chianti, but that's me ...
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.